From the Tri-City Herald
by Annette Cary
November 20, 2019
Work has halted at Hanford to remove a highly radioactive spill just north of Richland after an eighth incident this year in which a worker’s clothing or skin was contaminated with radioactive waste.
The 324 Building sits over a leak of radioactive cesium and strontium into the soil beneath it at the site about one mile north of Richland and about 300 yards west of the Columbia River.
“Although individually the contamination levels (on workers) have been low and no dose has been assigned to workers, collectively the number of personnel contamination events indicate a negative trend in contamination control that corrective actions taken to date have been inadequate to address,” the Department of Energy wrote in a Nov. 14 letter to its contractor on the project, CH2M Hill Plateau Remediation Co.
Dose is a calculation of the radioactive exposure to the worker.
“(The Richland Operations Office) expects that workers at Hanford are protected from personnel radiological contamination while accomplishing our important Hanford mission,” Franco said.
The building has been left standing over the contaminated spill and the contamination to workers had been contained within the building, so the public is not at risk.
The building prevents precipitation from reaching the spill beneath it to carry it closer to the groundwater and also can be used to shield workers from radiation.
324 BUILDING WORK COMPLICATED
After the Tri-City Herald asked DOE for information about the Nov. 14 letter, Brian Vance sent a message to all Hanford employees on Wednesday afternoon saying that work within the building continues to be challenging “due to the high levels of radioactivity in the soil beneath the building.”
CH2M is working on improving “radiological practices and controls in the building by taking a holistic look at the full spectrum of operations,” Vance said. “Cleanup work in radiologically controlled areas inside the building will not resume without proper DOE oversight and approval.”
Ty Blackford, president of CH2M at Hanford, also sent a message to his employees Wednesday afternoon saying that work at the 324 Building has become more complicated.
He said work was stopped late last week after low-level contamination was discovered on an employee’s skin as they were leaving an area known to be contaminated within the building and checks were being done.
“The employee was easily decontaminated using standard techniques,” Blackford said.
In an incident in the spring in which a speck of contamination was found on the pant leg of an employee who was checking workers as they left a radiologically contaminated area, a piece of tape was used to remove the contamination.
“Each time we’ve encountered challenges at the project this past year, the team did the right thing by stopping work, evaluating conditions and determining the safest path forward,” Blackford said.
For the latest review of work processes, a team of experts is being assembled both from CH2M at Hanford and also from Jacobs Engineering, the owner of the Hanford contractor.
CONTAMINATION CONCERNS RAISED
The staff of the Defense Nuclear Facilities Safety Board also has been concerned about worker contamination and contamination spread within the building.
In the staff’s weekly report dated June 28, it noted that there had been a fourth case of a worker’s personal clothing being contaminated and the first case of skin contamination since February.
That week contamination was found on both a worker’s clothing and his skin.
If the protective clothing that workers wear becomes damp, the contamination can wick through to their personal clothing underneath and their skin, the report said.
As work was temporarily stopped in June, CH2M focused on ways to improve contamination, including requiring workers to wear water-impermeable outer coveralls, using adhesive paper and wet rags for added dust control, and limiting water injection during drilling.
Much of the focus of the review was on preventing the spread of contamination as workers were taking of their protective clothing layer and leaving contaminated areas, according to the defense board staff report.
But worker contamination continued to be a problem, including when contamination was found on a worker’s personal clothing in September, according to the defense board staff.
The clothing may have been contaminated as he took off protective clothing, and CH2M again changed processes for taking off protection clothing.
Contamination issues are tied to two projects being done in the building.
The contamination spill was within a hot cell, where work was done with highly radioactive material by workers manipulating equipment outside the building. The highly acidic strontium and cesium that spilled within the hot cell in the 1980s ate through stainless steel to reach the soil beneath.
Plans call for sawing out the bottom of the hot cell using remotely operated equipment and then digging up the most highly contaminated soil with an excavator arm mounted on the 30-foot-high, 5-foot-thick walls of the hot cell.
DOE officials have said the contamination beneath the building is so radioactive that it would be fatal within a few minutes of human contact.
DRILLING SPREADS CONTAMINATION
Before the bottom of the hot cell can be chopped and sawed up and then the contamination beneath it dug up, radioactively contaminated debris left in the hot cell has to be removed.
Some of the contamination events have involved the employees doing that work.
Other contamination events have been related to drilling being done into the soil beneath the building as part of a project to keep the building stable once part of the flooring and foundation is removed to allow digging.
Plans call for installing pilings beneath the building to stabilize it.
But as drilling has been done from within the building, contamination has spread.
In one incident in June contamination was found on a worker’s boots as he took off the protective clothing and was checked as he left the room where drilling was being done.
The next week was when the first incident of skin contamination since February occurred on a worker who was decontaminating the room where the drilling was being done.
“The 324 Building presents complex challenges and the department is committed to safe and deliberate completion of this project,” Vance said.
Workers with Hanford’s CH2M Hill Plateau Remediation Co. have removed, packaged and shipped 15 bins of contaminated waste from the 324 Building since July. COURTESY DEPARTMENT OF ENERGY
Shipped where?
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